I think usually the way to go is the other way around; you find something interesting you want to do and look up how to do that. In the process you will most likely find answers that include tools that come with kali.

If you need some ideas maybe TryHackMe (more beginner friendly) or HackTheBox (kinda expects you to know what you are looking for) are good places to start. There's also tons of write-ups and videos about both of those should you get stuck at any place for too long.

Have fun!

You should have a look for capture the flags for penetration testing.

TryHackMe currently has a free Christmas program which has a beginner focus and outside of that they have a mix of free and paid for content (don't be tricked into feeling you need to pay if you just want the free content, navigate about a bit)

I've done some of the content and CTFs at HackerOne and I have heard of people liking HackTheBox too although I haven't done anything over there myself.

Hopefully that gives you some inspiration and guidance to get started!

Do you have experience with Linux? If you don't I would just stick with a regular distro. If you want to use Kali install it in a VM.